Billions of cans are produced annually for the packaging of beer, soda and other beverages. Despite the fact that these containers are used once and then discarded, they are produced with a high level of precision. These manufacturing procedures and tolerances are prompted by the need to achieve a high utilization of material since even minor savings on materials can be substantial when accumulated for such high levels of production.
One of the major features on the present day beverage container is the retained tab for the easy open end. This tab is designed to remain attached to the end, even despite repeated attempts to remove it from the opened container. The most common retained tab today is the lever tab where the tab, which is riveted to the end panel, extends over a scoreline so that the nose of the tab rests on the displaceable pour panel of the end. By grasping the rear or lift of the tab, it is possible to pivot the tab about the nose so that the tab acting as a second class lever pulls up and pops the scoreline thereby initiating rupture of the score just forward of the rivet. After initial rupture, the lever fulcrum shifts from the tab nose to the edge of the pour hole and the tab acting now as a first class lever causes the encircling scoreline to tear and the pour panel to be displaced inwardly as the tab nose swings downwardly into the container.
Considerable force must be exerted on the tab to effect full opening of the container, and accordingly the tab must be made sufficiently strong to resist failure prior to or during the opening process. Failure of the tab can occur by buckling of the tab along the line of maximum bending moment, just forward of the rivet; by tear through of the tongue, wherein the tongue lance tears on into the tab nose, or by collapse of the nose structure.
Tabs are strengthened by a high level of configuration such as ribbing etc and by the use of multiple layers of metal or metals. Reduced to its elemental form, the tab is merely a lever for which the designer expends materials. The material efficiency of the lever can be assessed by comparing the mechanical advantage of the tab with the weight of material employed in the fabrication of the tab.
Accordingly, it is the primary object of the instant invention to provide a lever tab structure for an easy open end which is sufficiently strong to operate effectively, but which exhibits a high material efficiency.
It is further an object of the instant invention to provide a lever tab structure which is simple to manufacture.
Finally, it is an object of the instant invention to provide a lever tab which is manufactured from a material which is compatible with the can end closure thereby facilitating material recovery.